JP-2007-267578A describes an energy transfer device which charges a vehicle battery using microwave and an object detecting device which detects a foreign matter located between a power-sending coil and a power-receiving coil in the energy transfer device. The object detecting device includes a camera which images a space between the power-sending coil and the power-receiving coil, and a processor which processes the image data taken by the camera so as to detect a foreign matter as an obstacle. If it is determined that there is an obstacle, the processor stops sending the microwave. Thus, energy loss caused by the obstacle can be avoided, and the irradiation of the microwave to the obstacle can be stopped.
However, it is required to keep a predetermined brightness for the space between the power-sending coil and the power-receiving coil in order to take the image with the camera. Therefore, lighting is continuously needed in night, because it is dark around the space at night, while detecting a foreign matter.